Our on-going research during the last year is that 1) we have developed a tissue-clearing method to map the physical patterns of sympathetic and parasympathetic nerve branching in the myocardium as well as the cardiac conduction system including the His-Purkinje system, and 2) we have developed a 3D co-culture system of iPS-derived cardiomyocytes with sympathetic neurons, endothelial cells, and epicardial cells to examine whether the co-cultured cardiomyocytes improve structural and gene expression properties. In a similar line of experiments, we are analyzing mutants lacking sympathetic nerves to examine what happens to the myocardium development and conduction system architecture in the absence of sympathetic innervation. These studies will provide a mechanistic framework for the developmental program of the neuro-vascular patterning and the functional consequence of sympathetic innervation in the developing heart.